Surface Tension

Total Page：16

File Type：pdf, Size：1020Kb

California State University of Bakersfield, Department of Chemistry Surface Tension Standard: 2-PS1-1. Plan and conduct an investigation to describe and classify different kinds of materials by their observable properties. Introduction: You’re about to see three important forces tugging on droplets water: gravity, cohesion, and adhesion. Gravity flattens the droplets, cohesion holds the droplets together, and adhesion holds the drops on the surface of the coin. The cohesive force is the pull of the water molecules on themselves. Each successive drop sticks to the water that’s already on the coin. We often call this cohesive force “surface tension”. It’s what makes water drops look like they’re wrapped in invisible skins. Soap reduces the cohesive force, and breaks the surface tension. Soapy water makes smaller drops than plain water. Since soapy drops are smaller, more soapy drops will fit on a penny than plain water drops. Materials: An eye-dropper A penny Liquid dish-soap A glass of water Safety: Always have an adult with you to help you during your experiment. Always wear eye protection and gloves when doing chemistry experiments Procedure: Part 1 1. Guess how many water drops you can fit on the front of a penny. 2. Try it. How many drops will stay on the face of a penny without spilling water off the sides? 3. Repeat the experiment, say, three times. The number of drops will probably come out about the same each time. 4. Each time you do it, write down the number of drops. Part 2 1. Add a tablespoon of dish soap to your glass of water. Stir gently, don’t make too many bubbles. 2. How many soapy drops can you fit on the front of a penny now? Questions: How many drops did you get on the penny with only water? How many drops did you get on the penny with soap and water? References: 1. Billnye.com. http://www.billnye.com/for-kids-teachers/home-demo-details/ (accessed July 17, 2012). .

Copy Link

Recommended publications

Glossary Physics (I-Introduction)
1 Glossary Physics (I-introduction) - Efficiency: The percent of the work put into a machine that is converted into useful work output; = work done / energy used [-]. = eta In machines: The work output of any machine cannot exceed the work input (<=100%); in an ideal machine, where no energy is transformed into heat: work(input) = work(output), =100%. Energy: The property of a system that enables it to do work. Conservation o. E.: Energy cannot be created or destroyed; it may be transformed from one form into another, but the total amount of energy never changes. Equilibrium: The state of an object when not acted upon by a net force or net torque; an object in equilibrium may be at rest or moving at uniform velocity - not accelerating. Mechanical E.: The state of an object or system of objects for which any impressed forces cancels to zero and no acceleration occurs. Dynamic E.: Object is moving without experiencing acceleration. Static E.: Object is at rest.F Force: The influence that can cause an object to be accelerated or retarded; is always in the direction of the net force, hence a vector quantity; the four elementary forces are: Electromagnetic F.: Is an attraction or repulsion G, gravit. const.6.672E-11[Nm2/kg2] between electric charges: d, distance [m] 2 2 2 2 F = 1/(40) (q1q2/d ) [(CC/m )(Nm /C )] = [N] m,M, mass [kg] Gravitational F.: Is a mutual attraction between all masses: q, charge [As] [C] 2 2 2 2 F = GmM/d [Nm /kg kg 1/m ] = [N] 0, dielectric constant Strong F.: (nuclear force) Acts within the nuclei of atoms: 8.854E-12 [C2/Nm2] [F/m] 2 2 2 2 2 F = 1/(40) (e /d ) [(CC/m )(Nm /C )] = [N] , 3.14 [-] Weak F.: Manifests itself in special reactions among elementary e, 1.60210 E-19 [As] [C] particles, such as the reaction that occur in radioactive decay.
[Show full text]
Water Olympics, They Will Each Fold and Float: Need a Copy of the Score Card
WMER OLYMPICS I. Topic Area molecules and the paper fibers is greater than the Properties of water cohesive force between the water molecules. This causes the water molecules to be pulled up the paper towel Il. Introductory Statement against the force of gravity. The attraction between unlike This is a series of four activities that deal with some of molecules is called adhesion. the properties of water. The activities are short and may Bubble Rings: See the background information in the be done one at a time or all together in an “Olympic” “Bubble Busters” activity in this book. format. The activities can be used as an introduction to a water unit with the students discovering some of the VII. ManagementSuggestions properties of water, or they can be used as culminating These four activities may be done as individual lessons activities. Either way, it is important that the children or as centers in an “olympic” format with students rotating discuss the properties of water they have observed after through the activities. The task cards can be run off and doing the activities. placed at each center. Students should be responsible for cleaning up a center before moving on to the next one. III. Math Skills Science Processes An extra supply of paper towels may be placed at each a. Computation a. Observing center to facilitate clean up. It is important that these ac- b. Measuring b. Predicting tivities be followed by class discussions which focus on c. Collecting and recording the water properties involved. data d. Controlling variables VIII. Procedure The procedures for each activity are given on the task IV.
[Show full text]
11 Fluid Statics
CHAPTER 11 | FLUID STATICS 357 11 FLUID STATICS Figure 11.1 The fluid essential to all life has a beauty of its own. It also helps support the weight of this swimmer. (credit: Terren, Wikimedia Commons) Learning Objectives 11.1. What Is a Fluid? • State the common phases of matter. • Explain the physical characteristics of solids, liquids, and gases. • Describe the arrangement of atoms in solids, liquids, and gases. 11.2. Density • Define density. • Calculate the mass of a reservoir from its density. • Compare and contrast the densities of various substances. 11.3. Pressure • Define pressure. • Explain the relationship between pressure and force. • Calculate force given pressure and area. 11.4. Variation of Pressure with Depth in a Fluid • Define pressure in terms of weight. • Explain the variation of pressure with depth in a fluid. • Calculate density given pressure and altitude. 11.5. Pascal’s Principle • Define pressure. • State Pascal’s principle. • Understand applications of Pascal’s principle. • Derive relationships between forces in a hydraulic system. 11.6. Gauge Pressure, Absolute Pressure, and Pressure Measurement • Define gauge pressure and absolute pressure. • Understand the working of aneroid and open-tube barometers. 11.7. Archimedes’ Principle • Define buoyant force. • State Archimedes’ principle. • Understand why objects float or sink. • Understand the relationship between density and Archimedes’ principle. 11.8. Cohesion and Adhesion in Liquids: Surface Tension and Capillary Action • Understand cohesive and adhesive forces. • Define surface tension. • Understand capillary action. 11.9. Pressures in the Body • Explain the concept of pressure the in human body. • Explain systolic and diastolic blood pressures. • Describe pressures in the eye, lungs, spinal column, bladder, and skeletal system.
[Show full text]
Adhesion and Cohesion
Hindawi Publishing Corporation International Journal of Dentistry Volume 2012, Article ID 951324, 8 pages doi:10.1155/2012/951324 Review Article Adhesion and Cohesion J. Anthony von Fraunhofer School of Dentistry, University of Maryland, Baltimore, MD 21201, USA Correspondence should be addressed to J. Anthony von Fraunhofer, [email protected] Received 18 October 2011; Accepted 14 November 2011 Academic Editor: Cornelis H. Pameijer Copyright © 2012 J. Anthony von Fraunhofer. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The phenomena of adhesion and cohesion are reviewed and discussed with particular reference to dentistry. This review considers the forces involved in cohesion and adhesion together with the mechanisms of adhesion and the underlying molecular processes involved in bonding of dissimilar materials. The forces involved in surface tension, surface wetting, chemical adhesion, dispersive adhesion, diﬀusive adhesion, and mechanical adhesion are reviewed in detail and examples relevant to adhesive dentistry and bonding are given. Substrate surface chemistry and its inﬂuence on adhesion, together with the properties of adhesive materials, are evaluated. The underlying mechanisms involved in adhesion failure are covered. The relevance of the adhesion zone and its impor- tance with regard to adhesive dentistry and bonding to enamel and dentin is discussed. 1. Introduction molecular attraction by which the particles of a body are uni- ted throughout the mass. In other words, adhesion is any at- Every clinician has experienced the failure of a restoration, be traction process between dissimilar molecular species, which it loosening of a crown, loss of an anterior Class V restora- have been brought into direct contact such that the adhesive tion, or leakage of a composite restoration.
[Show full text]
Cohesion and Adhesion with Proteins
Cohesion and Adhesion with Proteins Charles R. Frihart Forest Products Laboratory Madison, WI 53726, USA [email protected] Introduction These aggregates can be broken up and may be somewhat uncoiled at pH extremes, especially at high pH conditions, With increasing interest in bio-based adhesives, re- when electrostatic repulsion overcomes hydrophobic at- search on proteins has expanded because historically they traction. Additions of chaotropic agents, some surfactants, have been used by both nature and humans as adhesives. A and certain salts are also used to disaggregate and maybe wide variety of proteins have been used as wood adhe- somewhat uncoil the protein structure. sives. Ancient Egyptians most likely used collagens to bond veneer to wood furniture, then came casein (milk), Table 1. Important reactive components in soy pro- blood, fish scales, and soy adhesives, with soybeans and teins as percent of total protein weight. caseins being important for the development of the ply- Amino Acid Structure % Soy Protein wood and glulam industries. Despite many years of re- - + H2NH2CH2CH2CH2C CH COO Na search on developing adhesive products, it is not clear how Lysine NH2 6.4 the proteins provide good adhesive strength, but some N - + thoughts are expressed here. CH2 CH2 COO Na Histidine N 2.6 H NH2 Protein Structure NH - + Arginine H2N C NHCH2CH2CH2 CH COO Na 7.3 NH2 Understanding protein macromolecular structure is a - + prerequisite for understanding properties because protein Tyrosine HO CH2 COO Na 3.8 structure is so different from that of other adhesives. Ex- NH2 - + cept for structural proteins, such as silk, collagen, and ker- CH2 COO Na Tryptophan 1.4 atin, proteins mainly form globular shapes due to the hy- NH2 N drophobicity of their protein sequences.
[Show full text]
Unique Properties of Water!
Name: _______ANSWER KEY_______________ Class: _____ Date: _______________ Unique Properties of Water! Word Bank: Adhesion Evaporation Polar Surface tension Cohesion Freezing Positive Universal solvent Condensation Melting Sublimation Dissolve Negative 1. The electrons are not shared equally between the hydrogen and oxygen atoms of water creating a Polar molecule. 2. The polarity of water allows it to dissolve most substances. Because of this it is referred to as the universal solvent 3. Water molecules stick to other water molecules. This property is called cohesion. 4. Hydrogen bonds form between adjacent water molecules because the positive charged hydrogen end of one water molecule attracts the negative charged oxygen end of another water molecule. 5. Water molecules stick to other materials due to its polar nature. This property is called adhesion. 6. Hydrogen bonds hold water molecules closely together which causes water to have high surface tension. This is why water tends to clump together to form drops rather than spread out into a thin film. 7. Condensation is when water changes from a gas to a liquid. 8. Sublimation is when water changes from a solid directly to a gas. 9. Freezing is when water changes from a liquid to a solid. 10. Melting is when water changes from a solid to a liquid. 11. Evaporation is when water changes from a liquid to a gas. 12. Why does ice float? Water expands as it freezes, so it is LESS DENSE AS A SOLID. 13. What property refers to water molecules resembling magnets? How are these alike? Polar bonds create positive and negative ends of the molecule.
[Show full text]
Multidisciplinary Design Project Engineering Dictionary Version 0.0.2
Multidisciplinary Design Project Engineering Dictionary Version 0.0.2 February 15, 2006 . DRAFT Cambridge-MIT Institute Multidisciplinary Design Project This Dictionary/Glossary of Engineering terms has been compiled to compliment the work developed as part of the Multi-disciplinary Design Project (MDP), which is a programme to develop teaching material and kits to aid the running of mechtronics projects in Universities and Schools. The project is being carried out with support from the Cambridge-MIT Institute undergraduate teaching programe. For more information about the project please visit the MDP website at http://www-mdp.eng.cam.ac.uk or contact Dr. Peter Long Prof. Alex Slocum Cambridge University Engineering Department Massachusetts Institute of Technology Trumpington Street, 77 Massachusetts Ave. Cambridge. Cambridge MA 02139-4307 CB2 1PZ. USA e-mail: [email protected] e-mail: [email protected] tel: +44 (0) 1223 332779 tel: +1 617 253 0012 For information about the CMI initiative please see Cambridge-MIT Institute website :- http://www.cambridge-mit.org CMI CMI, University of Cambridge Massachusetts Institute of Technology 10 Miller’s Yard, 77 Massachusetts Ave. Mill Lane, Cambridge MA 02139-4307 Cambridge. CB2 1RQ. USA tel: +44 (0) 1223 327207 tel. +1 617 253 7732 fax: +44 (0) 1223 765891 fax. +1 617 258 8539 . DRAFT 2 CMI-MDP Programme 1 Introduction This dictionary/glossary has not been developed as a deﬁnative work but as a useful reference book for engi- neering students to search when looking for the meaning of a word/phrase. It has been compiled from a number of existing glossaries together with a number of local additions.
[Show full text]
SUGGESTED ACTIVITIES (States of Matter)
SUGGESTED ACTIVITIES (States of Matter) From Invitations to Science Inquiry 2nd Edition by Tik L. Liem: Activity Page Number Concept • Can the container hold more? 91 Molecular spacing • The shrinking balloon 92 Molecular spacing • The shrinking mixture of liquids 93 Molecular spacing • The clinging water streams 108 Cohesion • The smaller, the stronger 109 Capillary action • Pour water along a string 110 Adhesion • Where does the cork float? 111 Surface tension • How many pennies can go in? 112 Surface tension • The detergent propelled boat 115 Surface tension From NSF/IERI Science IDEAS Project (See following pages): Activity Page Number Concept • Kids as molecules See following pages Molecular spacing • Poured gas “ “ “ States of Matter • Sticky water “ “ “ Adhesion • The shrinking mixture of liquids w/ measurement Molecular spacing • A”Mazing” Water “ “ “ Cohesion • Cheesecloth Demo “ “ “ Cohesion/Adhesion • Magic Pepper Sinker “ “ “ Cohesion • Merging Streams “ “ “ Cohesion • Pour Water sideways “ “ “ Cohesion/Adhesion • Where does the cork float “ “ “ Surface tension • Magical drops “ “ “ Surface tension • Propel the boat “ “ “ Cohesion From Harcourt Science Teacher’s Ed. Unit E: (For ALL grade levels) Activity Page Number Concept • Solids are smaller E17 (3rd grade text) Molecular spacing NSF/IERI Science IDEAS Project Grant #0228353 CAN THE CONTAINER HOLD MORE? A. Question: How much can a container really hold? B. Materials Needed: 1. A transparent container (glass or plastic). 2. Marbles, sand water and a graduated beaker. C: Procedure: 1. Fill the transparent container up to the brim with marbles. 2. Show the students that you still have sand and water; ask them: “Can I add any other material to this container?” 3. Add sand to the container (shake to settle the sand in between the marbles); ask the same question again.
[Show full text]
Water Drops on a Penny
Water Drops on a Penny Introduction SCIENTIFIC Why do water droplets bead when dropped on a waxy surface? Why can some insects walk on water? These observations can be attributed to the high surface tension of water. Surface tension is the result of attractive forces between molecules. Water’s large contribution to life on Earth depends on its unique properties. Without it, life on Earth would be impossible. Concepts • Cohesion • Polarity • Surface tension • Surfactants Materials Beaker, 50-mL Pipets, disposable, 2 Dish soap, liquid Water, tap Paper towels Pennies, 2 Safety Precautions Although this activity is considered nonhazardous, please follow all laboratory safety guidelines. Wash hands thoroughly with soap and water before leaving the laboratory. Procedure Part A. 1. Rinse a penny in tap water. Dry thoroughly with a paper towel. 2. Place the penny on a fresh paper towel. 3. Fill a beaker with 25 mL of tap water. 4. Using a pipet, slowly drop individual droplets of water onto the surface of the penny. 5. Count each drop until the water begins to spill over the sides of the penny. Record your observations in a data table. Note: Watch the penny from above rather than from the side while making observations. 6. Repeat steps 1–5 for a total of 3 trials. Thoroughly dry the penny between each trial. Part B. 1. Rinse a new penny in tap water. Dry thoroughly with a paper towel. 2. Place the penny on a fresh paper towel. 3. Fill a beaker with 25 mL of tap water. Add 2 drops of liquid dish soap to the beaker and stir.
[Show full text]
Water and Life: the Molecule That Supports All Live Water and Life: the Molecule That Supports All Life
BIOLOGY 101 CHAPTER 3: Water and Life: The Molecule that supports all Live Water and Life: The Molecule that Supports all Life CONCEPTS: • 3.1 Polar covalent bonds in water molecules result in hydrogen bonding • 3.2 Four emergent properties of water contribute to Earth's suitability for life • 3.3 Acidic and basic conditions affect living organisms Water and Life: The Molecule that Supports all Life OVERVIEW: • The physical properties of water are dictated by the laws of thermodynamics The First Law of Thermodynamics Energy cannot be created or destroyed, it can only be transformed The Second Law of Thermodynamics The total entropy of an isolated system always increases over time or… High energy systems spontaneously change to lower energy systems Water and Life: The Molecule that Supports all Life 3.1 Polar covalent bonds in water molecules result in hydrogen bonding: • A water molecule is shaped like a wide V, with two hydrogen atoms joined to an oxygen atom by single polar covalent bonds. • Because oxygen is more electronegative than hydrogen, a water molecule is a polar molecule in which opposite ends of the molecule have opposite charges. ✓ Polar molecules have a separation of charges, having both positively and negatively charged regions Water and Life: The Molecule that Supports all Life 3.1 Polar covalent bonds in water molecules result in hydrogen bonding: • A water molecule is shaped like a wide V, with two hydrogen atoms joined to an oxygen atom by single polar covalent bonds. • Because oxygen is more electronegative than hydrogen, a water molecule is a polar molecule in which opposite ends of the molecule have opposite charges.
[Show full text]
Cohesion and Adhesion in Liquids: Surface Tension and Capillary Action∗
Connexions module: m42197 1 Cohesion and Adhesion in Liquids: Surface Tension and Capillary Action∗ OpenStax College This work is produced by The Connexions Project and licensed under the Creative Commons Attribution License 3.0y Abstract • Understand cohesive and adhesive forces. • Dene surface tension. • Understand capillary action. 1 Cohesion and Adhesion in Liquids Children blow soap bubbles and play in the spray of a sprinkler on a hot summer day. (See Figure 1.) An underwater spider keeps his air supply in a shiny bubble he carries wrapped around him. A technician draws blood into a small-diameter tube just by touching it to a drop on a pricked nger. A premature infant struggles to inate her lungs. What is the common thread? All these activities are dominated by the attractive forces between atoms and molecules in liquidsboth within a liquid and between the liquid and its surroundings. Attractive forces between molecules of the same type are called cohesive forces. Liquids can, for example, be held in open containers because cohesive forces hold the molecules together. Attractive forces between molecules of dierent types are called adhesive forces. Such forces cause liquid drops to cling to window panes, for example. In this section we examine eects directly attributable to cohesive and adhesive forces in liquids. : Attractive forces between molecules of the same type are called cohesive forces. : Attractive forces between molecules of dierent types are called adhesive forces. ∗Version 1.5: Feb 20, 2014 10:48 am +0000 yhttp://creativecommons.org/licenses/by/3.0/ http://cnx.org/content/m42197/1.5/ Connexions module: m42197 2 Figure 1: The soap bubbles in this photograph are caused by cohesive forces among molecules in liquids.
[Show full text]
Observing and Describing Cohesion, Surface Tension, and Adhesion
Science 5 Life LESSON 37 Physical Earth and Space Observing and describing cohesion, surface tension, and adhesion Lesson Preparation Science Word List C Program Materials • Child’s Booklet C Investigating Matter and Its Interactions cohesion (pp. 6–8) • Lesson 37 Slide Show (see website, Lesson 37) surface tension • Lesson Activity 37 adhesion • Science Word List C (see inset) • Lesson Review 37 Tool Kit Materials • Pipette Collected Materials • Yellow highlighter • Cup with water • Sandwich-size plastic bags • Small piece of aluminum foil • Paper towel • Penny The Lesson “In your last science lessons, you learned about matter changing state.” “Let’s review what you learned.” “Take out your chemistry booklet and highlighter.” • Allow time for your child to do this. “Open your booklet to pages 6 and 7.” “What happens during the process of condensation?” A gas changes to a liquid. “What happens during the process of ionization?” A gas changes to plasma. “What is the process of plasma changing to a gas called?” deionization 254 © Nancy Larson. All rights reserved. Reproduction prohibited. Science 5, Lesson 37 “What happens during the process of sublimation?” A solid changes to a gas. “What is the process of a gas changing to a solid called?” deposition “What happens during the process of vaporization?” A liquid changes to a gas. “What are two types of vaporization?” boiling and evaporation “What are two ways boiling and evaporation differ?” Boiling occurs throughout the liquid and evaporation occurs only at the surface of the liquid; boiling occurs at the liquid’s boiling point and evaporation occurs at temperatures below the boiling point.
[Show full text]